1. Field of the Invention
The present invention relates generally to materials testing, and more particularly to a device and method for measuring the adhesion strength of a coating to a substrate.
2. Description of Related Art
A variety of coatings are commonly applied to surfaces of substrates to enhance or otherwise alter characteristics of the substrate. For example, coatings such as corrosion barriers, paint, adhesives, moisture barriers, vapor barriers, and sheet materials are often applied to substrates formed of materials such as metals, cementitious materials, wood, or plastics.
The durability and longevity of a coating is highly dependent on the strength of the adhesion to the substrate over which it is applied. The ability to measure the adhesion strength of coatings is a useful quality control criterion that is sometimes used for acceptance or rejection of coatings application work, and/or to compare the relative qualities of different coating materials. Also, preliminary coating adhesion testing can be used to evaluate a substrate surface to determine if additional surface preparation is needed before applying a final coating to the substrate. See, e.g., Jon Steele and C. Jay Steele, Critical Performance Characteristics for Corrosion Barrier Coatings Applied to Concrete, and Jon Steele, Testing Adhesion of Coatings Applied to Concrete, 33 MATERIALS PERFORMANCE 33-36 (November 1994, NACE, International), both of which are incorporated herein by reference for background information regarding coating adhesion testing.
Currently, there are few effective methods of determining coating adhesion, especially the adhesion of coatings applied to concrete substrates. Many of the coating adhesion test devices that are currently available have been found to be unwieldy in use and unduly complex and expensive, especially for routine testing in the field. As a result, effective quality control of coating application and adhesion is often overlooked. Thus, it can be seen that needs exist for improved methods and devices for testing the adhesion of a coating to a substrate. It is to the provision of methods and devices meeting these and other needs that the present invention is primarily directed.
The present invention provides a testing apparatus and method for testing the adhesion of a coating to a surface. The invention also includes an improved testing dolly for use with the testing apparatus and method of the present invention. According to preferred forms, the apparatus and method of the present invention are simple, rugged, and inexpensive to manufacture and use, are readily adaptable to a wide variety of uses, and provide effective and accurate testing results.
Briefly described, in a preferred form, the present invention comprises a device for testing the adhesion of a coating to a substrate. The device preferably includes a beam having a first end, a second end, and an intermediate portion. The device preferably also includes a contact head connected to the first end of the beam. The device preferably also includes a pointer arm having a first end connected to the first end of the beam and a second free end opposite the first end. The device preferably also includes a scale mounted to the beam proximal the second end of the pointer. The device preferably also includes engagement means connected to the contact head for engaging a test dolly.
Otherwise defined, the present invention provides a device for testing the adhesion of a coating to a substrate, the device preferably including a beam having a first end, a second end, and an intermediate portion, a contact head connected to the first end of the beam, engagement means connected to the contact head for engaging a test dolly, and an indicator for indicating a magnitude of force applied by the device.
Still another aspect of the present invention provides a method of testing the adhesion of a coating to a substrate. The method preferably includes attaching a test dolly to a portion of a coating. The method preferably further includes coupling a testing device to the test dolly, the testing device comprising a beam, a contact head connected to a first end of the beam, engagement means for engaging the test dolly, and an indicator. The method preferably further includes applying sufficient force to a second end of the beam to detach the test dolly and an attached portion of the coating from the substrate. The method preferably further includes observing the indicator to determine a measure of adhesion of the coating to the substrate.
Still another aspect of the present invention provides a test dolly for testing the adhesion of a coating to a substrate. The test dolly preferably includes a base portion having an attachment face for adhesion to a portion of a coating, the base portion further including a plurality of straight sides. The test dolly preferably further includes an engagement feature for attachment to a testing device.
These and other features and advantages of the present invention are described herein with reference to the drawing figures, or will be readily apparent to those skilled in the art having been provided with the teaching herein.